Food Processing L3

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  1. who invented canning or "appertisation"?
    Nicolas Appert
  2. who established the microbiological basis for food spoilage?
    Louis Pasteur
  3. what is blanching?
    mild heat treatment given to fruits and vegetables prior to freezing, drying and canning
  4. when is blanching a primary method?
    • before freezing and drying
    • before canning
  5. why is blanching done before freezing and drying?
    for enzyme inactivation
  6. why is blanching done before canning?
    • expels intercellular gases (protects can integrity, better vacuum, better heat transfer)
    • softens tissue for more compact packing)
    • reduces product microbial load
  7. which oxidative enzymes does blanching protect against?
    peroxidase, catalase, polyphenol oxidase, lipase, lipoxygenase, pectin esterase
  8. what is known as the index of blanching?
    • peroxidase inactivation
    • because it is very heat resistant
    • wide occurrence in foods
  9. what is blanching time?
    • most vegetables (1-5min) boiling water or steam
    • corn-on-cob (7-10min)
  10. what is the blanching medium?
    water, steam, hot gas, microwave
  11. why is blanching energy intensive?
    • 35% of total energy in processing
    • 2/3 generally lost
    • energy use: steam-water-MW-air
  12. which types of blanching have more pollution?
    • water and steam
    • (air and microwave have less)
  13. how can you make blanching more efficient?
    • use an ABCO blancher (made by AAFC)
    • use the heat-hold-cool approach
    • steam heating and recycling
    • forced air cooling (fog-jet humidified)
  14. how are most products peeled?
    by hand
  15. which products are peeled with high pressure steam/water?
    potato, tomato
  16. which products are peeled abrasively?
    potato, carrot (roots)
  17. which products are peeled mechanically (knives)?
    apples, pears, pineapple
  18. how are products are peeled chemically?
    • lye peeling
    • caustic soda (NaOH) dissolve product skin
    • dip or spray product (concentration, temperature, time, agitation)
    • washing in acid dip
  19. how is a can declared "full"?
    by declared fill weight
  20. when is headspace not important?
    in hot-fill process
  21. when is headspace a must for containers?
    • at high temperature
    • under agitation (end-over-end and axial)
  22. what is exhausting?
    • the process of removing headspace as from cans
    • reduces strain on cans and jars during retorting
    • provides oxygen free environment (vacuum)
  23. what are the three methods of exhausting?
    • thermal exhausting
    • steam closing
    • mechanical vacuum sealing
  24. what is thermal exhausting?
    • hot filled cans conveyed through a steam chamber (exhaust box)
    • steam replaces air and can is sealed while hot
    • on condensation, steam leaves a vacuum energy intensive
  25. what is steam closing?
    • same principle as thermal exhausting
    • instead of slow exhausting, high pressure steam injected into cans prior to closing
    • more efficient
    • less energy intensive
  26. what is mechanical vacuum sealing?
    • clinched cans are subjected to vacuum
    • removes headspace air
    • high speed vacuum treatment (may not remove dissolved air from product)
  27. how are can dimensions expressed?
    give an example?
    • using 2 numbers (3 digits each) either in tin, steal, aluminum
    • ex: 401x411 (means 4 and 1/16" diameter from outside edge of both double seams, by 4 and 11/16" in height (outside edge of both terminal seams)
  28. what is the purpose of thermal processing?
    • to make the product safe and shelf-stable
    • reduce the number of microorganisms of public health concern to a statistically small level
    • create an environment around food to suppress the growth and activity of spoilage microorganisms
  29. what does the success of thermal processing depend on?
    • removing oxygen from package
    • controlling pH
    • giving adequate heat treatment
    • controlling the storage temperature
  30. how can recontamination be prevented once foods have been thermally processed?
    package the foods in hermetically sealed containers
  31. what are obligate aerobes?
    • microorganisms requiring oxygen to grow
    • ex: most molds
  32. what are facultative anaerobes?
    • microorganisms that can either make ATP using oxygen, but if no oxygen is available, they can use fermentation instead
    • ex: s.aureus
  33. what are obligate anaerobes?
    • microorganisms that grow without oxygen, some can even be killed by oxygen
    • ex: c. botulinum
  34. what is a low acid food?
    • pH ≥ 4.5
    • ex: all meats, fish, vegetables, most soups
  35. what is a medium acidic food?
    • pH 3.7-4.5
    • ex: fruit jams, fruit cocktails, grapes, tomato, peach, pimiento, pineapple, potato salad, prune juice, vegetable juice
  36. what are thermophylic bacteria?
    grow in 35-55°C
  37. what are mesophylic bacteria?
    grow in 10-40°C
  38. what are psychrophylic bacteria?
    grow in 0-35°C
  39. what is a high acid food?
    • pH < 3.7
    • ex: fruit juice, apple, berries, cherries,plum, sour pickles, sauerkraut, vinegar
  40. what is pasteurization?
    • mild heat treatment
    • destruction of pathogenic microorganisms
    • temporary shelf-life extension
    • product refrigerated to control spoilage
    • temperature applied (55-100°C)
    • lower the product temperature to below 4°C within 2 hrs after pasteurization
    • associated also with hermetically sealed packaging
    • for low acid product with refrigeration, added acids, added sugar or added salt
  41. what is sterilization?
    • also known as appertisation
    • application of heat for the purpose of shelf life extension and promotion of safety
    • more severe heat treatment
    • long term preservation
    • "misnomer" because product not sterile
    • "commercially sterile"
    • temperature applied of 100-150°C, reference T-121°C
    • associated with strong hermetically sealed packaging and storage at below 30°C (usually at room temp)
    • environment will prevent the growth of microorganisms of public health concern and spoilage type
  42. if a can is vacuum sealed (no obligate aerobes), what does pasteurization do to a high acid food?
    • control of vegetative bacteria, yeasts, molds, and enzymes
    • pathogens and spore formers inactive
    • shelf stable products for fruits and acidified foods
  43. if a can is vacuum sealed (no obligate aerobes), what does pasteurization do to a low acid food?
    • only pathogens controlled
    • bacterial spores active
    • only short term storage at refrigerated conditions
  44. if a can is vacuum sealed (no obligate aerobes), what does steriliization do to a high acid food?
    • public health concern: c. botulinum
    • bot cook - 12D process is required 
    • spoilage concern (non-pathogenic)
    • mesophylic obligate anaerobes (more resistant than facultative types)
    • heat resistant thermophiles are of no concern if stored below 30°C
Card Set:
Food Processing L3
2013-02-24 20:32:41
Food Processing L3

Food Processing L3
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